# Dehumidifier Vapor to Water Anatomy

How a refrigerant atmospheric water generator condenses vapour from room air on cold fins, then filters and treats it into drinking water\.

By quiet\-moon\-fa93a64e

Topic: Machines

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## Transcript

### 1. Midsection

The front shell is removed at the vertical mid\-plane of a refrigerant atmospheric water generator: a dehumidifier core followed by a treatment train\. The upper bay carries the filter, evaporator, condenser and centrifugal blower; the lower bay carries the rotary compressor, capillary, sump, pump and three treatment stages feeding the reservoir\.

Envelope 400 × 320 × 720 mm, within the 11–15 in footprint and 21–25 in height of the portable class\.

### 2. Intake and filtration

The blower draws room air through the left\-side louvre and a washable mesh filter into the coil face\. Blue dots are water vapour; grey dots are the dry\-air fraction\. Portable units are rated at 65 °F \(18\.3 °C\) dry bulb and 60 % RH\.

Rating condition: DOE test procedure, 10 CFR 430 Subpart B, Appendix X1\.

### 3. Evaporator: condensing below dew point

Boiling refrigerant holds the fin surface below the inlet dew point, 15\.3 °C for 21 °C at 70 % RH\. Vapour condenses on the fins, beads, coalesces and drains under gravity, releasing about 2\.45 MJ/kg of latent heat into the refrigerant\. Hydrophilic fin coatings limit bridging\. Below 0 °C the condensate freezes and the controller schedules a defrost\.

Slider: coil surface 18 °C to −2 °C\. Dew point by the Magnus formula\. Fins drawn at 6 mm pitch; production packs use about 1\.8–2\.5 mm\.

### 4. Drip pan and drain

Condensate leaves the fin pack as film and drops, collects in the drip pan and drains by gravity to the sump\. A float switch there starts the pump; in a plain dehumidifier the same switch stops the compressor when the bucket is full\. Refrigerant and condensate circuits never mix\.

### 5. Refrigerant circuit

The hermetic rotary compressor discharges hot gas to the condenser, where it rejects heat and liquefies\. The capillary tube, a fixed restrictor, drops the pressure; the cold two\-phase flow boils in the evaporator and returns through the accumulator as suction vapour\. Small portable units commonly run on R290 with a charge of roughly 60–70 g\.

Dots: red hot discharge gas, orange condensing liquid, blue cold two\-phase, pale blue suction vapour\.

### 6. Condenser reheat and exhaust

The near\-saturated air leaving the evaporator crosses the condenser and is reheated, so its relative humidity falls\. The forward\-curved wheel discharges it upward through the top grille, warmer than at intake by the compressor work plus the released latent heat\. No water forms on the condenser\.

### 7. Treatment train

Raw condensate is low in dissolved solids but not potable: coil biofilm and metals from the heat exchanger enter it\. The pump drives it through a 5 µm sediment cartridge, an activated\-carbon block and a UV\-C chamber, the last stage before storage\. A UV\-C lamp in the reservoir limits regrowth in stored water\.

UV\-C: mercury lamps 253\.7 nm, LEDs 265–280 nm\. NSF/ANSI 55 Class A requires at least 40 mJ/cm²; carbon claims fall under NSF/ANSI 42 and 53\.

### 8. Dispense

Treated water leaves the reservoir through the dispense line to the side tap\. Published field and review data put the energy cost at roughly 0\.3–0\.5 kWh per litre at 60–80 % RH, and yield falls steeply in dry air\.

Yield and energy depend strongly on inlet dew point; compare units only at a stated rating condition\.